Ridge surface system for maintaining laminar flow

Abstract

Abstract IN MANY APPLICATIONS WHERE FLUID FLOWS OVER A SOLID SURFACE, OR WHERE A BODY MOVES THROUGH A FLUID MEDIUM, LAMINAR, RATHER THAN TURBULENT OR SPERATED, FLOW IS DESIRABLE. FRICTION IN THE FLUID BOUNDARY LAYER IN COMBINATION WITH AN ADVERSE PRESSURE GRADIENT CAN CAUSE TURBULENCE OR SEPARATION EVEN ON A VERY SMOOTH SURFACE. AN ADVERSE PRESSURE GRADIENT EXISTS ON THE AFT PORTION OF MOST BODIES DUE TO THE DECELERATION OF FLUID WHICH HAS BEEN ACCELERATED OVER A CONVEX FORWARD PORTION. THE PRESENT INVENTION CREATES PATHS OF RELATIVELY FAVORABLE PRESSURE GRADIENT BY PROVIDING A SYSTEM OF SMOOTH RIDGES SHAPED AND LOCATED SUCH THAT THEY ACCELERATE CROSS FLOW COMPONENTS AS WELL AS THE FLOW IN THE FREE STREAM DIRECTION. THE RIDGES SWEEP SOME OF THE OUTER FLOW INTO THE BOUNDARY LAYER TO ENERGIZE THE LAYER IN AN ORDERLY FASHION. THE FLOW IN THE BOUNDARY LAYER IS ACCELERATED OVER THE RIDGES BECAUSE OF BOUNDARY LAYER THINNING AND BECAUSE THE RIDGES HAVE LESS CURVATURE THAN THE SURFACE. THEREFORE, THE RIDGES CAUSE LESS DECERLERATION OF THE FREE STREAM COMPONENTS THAN THE SURFACE, CREATING PATHS FOR RELATIVE ACCELERATION OF FLOW UP THE RIDGES. IN ADDITION, THE RIDGES MAY BE SHAPED IN LATERAL CROSS SECTION TO CREATE A VENTURI BETWEEN TWO RIDGES. IF THE RIDGES ARE EXTENDED BEYOND THE TRAILING EDGE OF THE SURFACE RELATIVELY FAVORABLE PRESSURE GRADIENTS CAN BE MAINTAINED TO THE SURFACE TRAILING EDGE. THE RIDGE SYSTEM PERFORMS THE FUNCTION OF ENERGIZING THE BOUNDARY LAYER IN THE MANNER OF VORTEX GENERATORS WITHOUT INTRODUCING TURBULENCE. THE RIDGE SYSTEM ALSO PERFORMS THE FUNCTION OF A BOUNDARY LAYER BLEED SYSTEM WITHOUT MECHANICAL COMPLEXITY.

Inventors

• 👤 Scott C Rethorst

Bibliographic Details